Method of making a matrix



Oct, 15, 1940. Q B CROWELL 2,218,35T

METHOD OF MAKING A MATRIX Filed Aug. 1S. 1931 @y Figi, i5 v Fiqf,

Inventor.

Patented Oct. 15, 1940 v l t l UNITED {STA-'ras PATENToFFlc-E signorto*` Viceroy Manufacturing` Company Limited, Toronto, Ontario, Canada fApplication Angine 1s, 1937, sei-'iai Norlzsasss '2 Claims; (Ci. 1r-25)yThe invention relates to vthe production of I:In my priorPatent2,075,50'l. granted March printing plates by a moulding processand more 30th, 1937, I discloseda'method rand means for particularly toan improved method and means the -production of non-metallic printing`plates for making the matrix from a reinforcedplastic and the presentinvention is directed to improve- 5 capable of being moulded inimpression-receiving ments therover which simplifythe process with- A5contact with an original printing plate, type or out sacrificingthedesired accuracy; the like. f v In the above yreferred to patentthelplasticizing The principal objects of theinvention are to andmoulding 'of -the matrix vmaterialwas carried reduce the cost and theamount of workl required out in one operation .while the entire plasticbody in the moulded production of printing plates and was confinedagainst spreading andrthe `plastic 10 to facilitate the formation of theprinting plate was `,thus forced into al1 cavities and spaces-btm mouldor matrix so that accurate printing plates tween the press heads and `afaithful mouldedA may be quickly and economically producedwithreproduction depended on the plastic being forced out subjecting theoriginal plates or type set Vup. to ll all of such cavities.V 1 It`frequently hap-rto damaging crushing pressure. i pened that incertaintype kset ups a considerable. 1.5

The principal features of the invention reside body of plastic wasrequired insorderfto :repro in the novel steps of forming the matrixbyfirst duce a comparatively. simple vprinting surfacer andplasticizinga suitable plastic under pressure in after the mouldingoperationit was necessary to association withV a bonding element to forma cutlor grind away the excessive portions of thel reinforced basecapable of receiving a moulded matrix. `'Ihe present, inventioneliminates vthis 20 impression with the, minimum body distortionnecessity by firstfincorporating a reinforcing ele and thereaftersubjecting said reinforced base to: mentiduring theinitial and partialstage of vul` a second plasticizing operation invpressure.- en.canization, after which the partially vvulcanizred gagement with anoriginal printing plate. type and reinforcedY sheet 4is subjectedtoffinalr andset up, or the like to permanently set said base Y completevulcanization while receiving this 25 Withfthe desired impressiontherein so thatrubmoulded impression-about a printinglplate or berprinting plates may be moulded directly. the like with theminimum-displacementiof the therefrom. y matrix material. A

'In the drawing, i ,In Figures 11andf2 I have illustrated aplateni'Figure 1 is an elevational vpartxs'ection l view of presshaving a heatedbasey l. and heated head 2.- 30

a platen press illustrating one form of reinforced In producing thematrix forming sheetaccordmatrix forming base receiving its initial heatand ing toFigure 1, I place a sheet 3 Ofsuitable wire' Pressuretreatment therein. screen on the base I and over this I arrange a Figure2 is a view similar to Figure 1 illuStratsheet 4 of unvulcanized rubber(or other suitable Y ing a modified fOrm 0f matrix forming baseunplastic material which may be advantageously 35 der initial treatmentin the Platen press. employed) and pressure and heat are appliedsoFigure 3 iS a Plan View partly broken aWaY that as the unvulcanizedsheet 4 is plasticized it ShOWirlg the initially treated Plastic baSeremoved will fill the various interstices in the wire screen from theDreSS- and permanently interlock therewith and form a 40 Figure 4 iS aperspective VieW 0f a portion 0f a. a. consolidated reinforced productready for use 40 preheated base showing a modied form of in in theseeondstep of the process. terrlal reillfOrCemellt- The heat andpressure is maintained only suf- Figure 5 is an elevational view partlyin seeyfioiently long enough to effect the partial vulcantion showing aportion of the preheated base ilization of the rubber sheet 4 and thepermanent j luStrated in Figures 3 and 4 subjected t0 a Silb-y bondingthereof with the Wire screen and I find 45 sequent heet and pressuretreatment in a platen that one-sixth to one-seventh of the normal fullpress in association with a metallic printing plate. vu1canizati0n isquite suitame, type Set up, 0r the like In the form of the inventionillustrated in Fig- Figure 6 is an enlarged fragmentary View 0f ure 2the wire screen is incorporated betweenv 5o Figure 5 Showing thematrixforming bese reeeivtwo rubber sheets 4 and 4' and vu1oanization is 5oing its nal moulded Shapealso carried out only partially asindicated in'Figure 7 iS a VieW Similar t0 Figure 6 ShOWing connection with theproduct illustrated in Figthe original metal printing plate, or type setup ure 1. removed andthe final rubber printing plate be- In Figure 3 thepartially vulcanized reinforced ing formed from the matrix. sheet isshown removed from the press after its 55 In Figures 5 and 6 the secondand separatev step in'the method is illustrated showing the cut-outpiece 5 placed in a vulcaiaingi'pressin association with a printingplate vt3 orother type set up which it is desired to reproduce,` whichprinting plate or other type `set upis shown with cavities 6therethrough, and it will be` noted, particularly on reference to Figure`6,`i that `o nly sufficient pressure is placed on the press to imbedthe raised `printing surfaces a slight-distance into the' body` of fthepart-vulcanized rmass fand that only avery limited local displacement ofthe adjacent faceof the 'mass' is brought about'v and thevpvlastic massldoes not flow into the cavities y6'."

This relation of the elements is maintained until-the vulcanization ofthe plastic forming body is completed after .which theplate l5 orothertype set upis removed. AI rubber printing plate is-now formedsby placinga thin sheetnrof unvulcanized rubber 1 over. the. impressed surfaceofthe matrix, the latter Vhaving-been pref-` erablyrst treated with asuitable parting sub# stance and by the application of heat and pres-vsurev the rubber sheet is vulcanized to receive and-permanently retain-the impressions of the matrix-to provide an accurate printing surface.The presence of theinternal interlocking reinforcing elements will, byreason of its having been first bonded,` and consolidated with the orprintingplate, thereby obtaining rubber ysheet during an initial step ofvulcanizing, eiectively retain Vthe matrix from ho'ri zontal expansionand distortion underv theheat and pressure applied to vulcanize thevnalsheet the desired accuracy. in the nal product. i

While the present invention has been developed in connection with amatrix or rubber subjected 'to successive vulcanizing steps; the processmay be carried out in connection with other plastics by rst subjectingthe same to a pre-plasticizing temperature in associationiwithv thereinforcing agent to rst effect a definite bonding of the two elementsafter which the reinforced and partially treated plastic will besubjected to a final plasticizing and/or permanent setting operation inimpression-receiving relation to a printing plate or other type set up.

The matrix. formed by `the above process may also be employed in theproduction of stereotypes or electrotypes as will be readily appreciatedby those skilled in the art, in which case the steps indicated inyFigure 7 will not be required. As

shown-in Figure 5 or 6 no barriers are required to confine thematrix-forming body against horizontal 'fexpansiom `this step, as shownin my formerpatented process referred to, being eliminated, since inthepresent case the entire matrixforming body isnot subjected to a uniformpressure .throughout and the reinforcing element is easily capable of c`confiningV the matrix bodily against the" very slight local expansionAforce What I claim as'my invention is:

-13 YThe method of producinaa ubbe mtfix forprintingplates whichcomprises rrst firmly permanently' associating uncured rubber with aforaminousqreinforcing element under such con'- ditions of heatandpressure as to eliminate internal voids and only' partially vulcanizethe rubber V'medium to substantially,one-sixth full vulcariization andrender the composite product substantially incapable of `subsequentcompression, and thereafter impressing the surface Withprintingcharacters and completing Ithe vulcanization of the rubberbefore removal of the said characters`- A.

2."Th'e method of producing aV rubber matrix for printing plates whichcomprises rstfirmlyv `permanently associating uncured rubber vwitha foraminous reinforcing element 'under such conditions ofheat and pressureas to eliminate internal voids and only partially vulcanize therubber'medium and render the composite product substantially 'incapableof subsequent compression, and thereafter `completing the' vulcanizationin a second 'step While maintaining print'- yin`g"charactersembeddedtherein onlya suf cient depth to effect local displacement ofthe rubber body While preventing contact of the rubber with-'the'depressedsurface areas of the printing characters.

` ORBY B. CROWELL.

